Are you new? Then you get OT after 40 hours in a week. If you made book....then It's OT after 5 hours a day. This may vary by local.
Do you have any vacation days available? DOUBT IT. But if you did....and could take a day if it wasn't peak....you are paid for 4 hours. Look at the bottom of your paystub...it will list any paid time off you have available....if any.
Don't think it matters what the national says, it's something that the language changes in nearly every local. Find your specific one for accurate information.